terminal
#
# apt-get install sudo (ubuntu, debian ecc ecc)
or For yum ( RPM ) distributions use this command to install sudo:
$
$ yum install sudo
add user sudo
$ usermod -aG sudo username (Debian, Ubuntu ecc)
or
$ usermod -aG wheel username (RedHat, , CentOS, Fedora ecc, "wheel" is standard group sudo )